This invention relates in general to ammunition and explosives and more particularly to a shaped charge explosive device.
Explosives and explosive devices have widespread use in military, antipersonnel, civil engineering and geological exploration applications. A vast number of factors may be varied in the control and use of such explosives and explosive devices to achieve a particular result. These factors include, among others, the design and arrangement of the component parts of such devices and the selection of the materials employed therein.
Shaped charge designs are frequently employed to provide a deep hole in a target material and to maximize crater volume. A shaped charge is usually a rotationally symmetric body of explosive material, which may be used alone or be positioned in a hollow charge casing. The charge is covered by an inverted conical liner made from a ductile metal and a detonator is located within the charge along its symmetry axis.
When the charge is detonated a detonation wave is generated causing the liner to collapse into two parts. One part bursts forward along the charge's symmetry axis as a jet of metal that travels at very high speed and penetrates the target. The other part, a metal slug, travels more slowly along the same axis, in the same direction as the preceding jet.
It has been observed that increasing the tip velocity of the jet increases the depth of penetration into many targets, including most metals and geological materials. The depth of penetration is critical for military targets and for releasing the flow of gas or oil in an oil well completion application.
Numerous factors affect the tip velocity of the jet. These include the chemical and physical properties of the materials from which the explosive device is formed as well as the geometries and relative positions of the component parts of the device and various techniques and constructions employed in assembling or constructing the device. Such techniques may include tapering the wall thickness or varying the shape of the shaped charge liner, altering the materials from which the liner is formed, varying the geometry or kind of explosive charge, or varying the geometry of or the material from which the casing is formed. Most of these prior art techniques involve major modifications to the explosive device operation, ultimately affecting the cost, ease of manufacture and transport of such devices.
Another method of improving the depth of penetration involves the use of a wave shaper. A wave shaper is a device that is positioned between the detonator and the liner to shape the detonation wave so that the wave impacts the liner at a more favorable angle, i.e., nearly normal or perpendicular to the liner. This improves the performance of the shaped charge and decreases the amount of explosive required to form a fast jet. Reducing the amount or height (with a fixed diameter round) of the explosive material can reduce the charge's length and weight. Wave shapers have been made of a variety of substances and materials, including metals, plastics, concrete and air, and may include a multitude of geometric shapes to allow proper contouring of the detonation wave.
Although conventional wave shapers are useful in shaping the detonation wave from a purely divergent wave front, such wave shapers frequently do not efficiently focus the energy of the detonation wave into contact with the shaped charge liner.